Plants need nutrients and water to grow. As they grow they remove the nutrients from the soil which, if they are not replaced, causes the soil to loose its fertility and crops yields start to decline. The nutrients can be replaced by leaving land fallow and ploughing the green manure in or by the addition of fertiliser.

Current practice today

Most subsistence farmers can not afford to buy chemical fertilisers and the need to provide food for their families precludes leaving land fallow. Some animal manure is applied directly to the land but many fields have no nutrient replacement programme and as a consequence crop yields are declining

Ambitions for a better solution

SOWTech believe that the farmers should be able to make their own fertiliser at their own farms by recycling their own wastes; animal human and kitchen waste. By doing so they can start to improve crop yields without investment in artificial fertilisers.

The "SOWTech Design"

Organic waste in the form of human waste, animal manures and kitchen waste contain the nutrients required for crop growth but they are not in a form readily available to the plants. By treating the waste using anaerobic digestion in Flexigester the complex molecules are broken down into simpler ones that are more easily absorbed by the plants. By taking up the nutrients the plants grow stronger and give and increased yield over those crops which have no fertiliser applied to them.

There are, however, concerns over the safety of using waste on land. Pathogens in the waste can remain viable in the soil and re-infect animals or humans if consumed. With the SOWTech Wrap-over Composting System the digestate from the Flexigester is applied to waste vegetation contained in breathable bags. Adding moisture to the vegetation helps with the composting process allowing the nutrients to be returned to the land.